Performance problem during send and batch send

[Gsantomaggio]

Describe the bug

We identified a bottleneck during the sending of messages and the receiving of confirmation flow.

Bot use https://github.com/rabbitmq/rabbitmq-stream-go-client/blob/main/pkg/stream/producer.go#L69 that is shared across the threads.

It reduces the performance of spending time on lock.

Need to fix:

• BatchSend
• Send

Reproduction steps

It is enough to execute the perf-test

Expected behavior

The publisher should be faster

Additional context

No response